Recently, voice-based digital assistants, such as Apple's SIRI, have been introduced into the marketplace to handle various tasks such as web searching and navigation. One advantage of such voice-based digital assistants is that users can interact with a device in a hands-free manner without handling or even looking at the device. Hands-free operation can be particularly beneficial when a person cannot or should not physically handle a device, such as when they are driving. However, to initiate the voice-based assistant, users typically must press a button or select an icon on a touch screen. This tactile input detracts from the hands-free experience. Accordingly, it would be advantageous to provide a method and system of activating a voice-based digital assistant (or other speech-based service) using a voice input or signal, and not a tactile input.
Activating a voice-based assistant using a voice input requires monitoring an audio channel to detect the voice input. This monitoring consumes electrical power, which is a limited resource on handheld or portable devices that rely on batteries and on which such voice-based digital assistants often run. Thus, it would be beneficial to provide an energy-efficient voice trigger that can be used to initiate voice- and/or speech-based services on a device.